.TH "QwtSystemClock" 3 "Thu Dec 11 2014" "Version 6.1.2" "Qwt User's Guide" \" -*- nroff -*-
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.SH NAME
QwtSystemClock \- 
.PP
\fBQwtSystemClock\fP provides high resolution clock time functions\&.  

.SH SYNOPSIS
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.PP
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\fC#include <qwt_system_clock\&.h>\fP
.SS "Public Member Functions"

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.RI "\fBQwtSystemClock\fP ()"
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.RI "\fIConstructs a null clock object\&. \fP"
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.RI "virtual \fB~QwtSystemClock\fP ()"
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.RI "\fIDestructor\&. \fP"
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.RI "bool \fBisNull\fP () const "
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.RI "void \fBstart\fP ()"
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.RI "double \fBrestart\fP ()"
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.RI "double \fBelapsed\fP () const "
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.SH "Detailed Description"
.PP 
\fBQwtSystemClock\fP provides high resolution clock time functions\&. 

Sometimes the resolution offered by QTime ( millisecond ) is not accurate enough for implementing time measurements ( f\&.e\&. sampling )\&. \fBQwtSystemClock\fP offers a subset of the QTime functionality using higher resolution timers ( if possible )\&.
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Precision and time intervals are multiples of milliseconds (ms)\&.
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\fBNote:\fP
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The implementation uses high-resolution performance counter on Windows, mach_absolute_time() on the Mac or POSIX timers on other systems\&. If none is available it falls back on QTimer\&. 
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.SH "Member Function Documentation"
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.SS "double QwtSystemClock::elapsed () const"

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\fBReturns:\fP
.RS 4
Number of milliseconds that have elapsed since the last time \fBstart()\fP or \fBrestart()\fP was called or 0\&.0 for null clocks\&. 
.RE
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.SS "bool QwtSystemClock::isNull () const"

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\fBReturns:\fP
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true if the clock has never been started\&. 
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.SS "double QwtSystemClock::restart ()"
Set the start time to the current time 
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\fBReturns:\fP
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Time, that is elapsed since the previous start time\&. 
.RE
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.SS "void QwtSystemClock::start ()"
Sets the start time to the current time\&. 

.SH "Author"
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Generated automatically by Doxygen for Qwt User's Guide from the source code\&.
